| Summary: | 碩士 === 中國文化大學 === 應用化學研究所 === 98 === This computational research is about alkaline earth metal (AEM) atom adsorbed on the small Silicon cluster Si2~Si6. We obtained the structures of lowest-lying hybrid clusters and investigated their geometric, electronic, and bond length. We used the B3LYP/6-311++G (3df) basis function to array out the B3LYP density functional theory (DFT) computation for Be, Mg, Ca adsorption. For big elements Sr and Ba we used the B3LYP/LANL2DZ computation method. Our results show that Be adsorption on the substrate of silicon clusters can result into large valency that predicted by conventional valence bond theory for Be. The Be-Si bonds are nearly non-polarized covalent bonds as indicated by Hirshfeld charges. On the other Ca, Sr, Ba form ionic bonds with Si. In general, the Be-Sin clusters have HOMO-LUMO gaps larger than 2.0 eV, which may make them good candidate for optoelectronic materials. Other hybrid clusters have smaller HOMO-LUMO gaps probably due to less covalent interactions between metals and silicon.
We also discovered the transition state structures for Be-Si4 isomer-intetrconversion by the QST2 and QST3 optimization at the B3LYP/6-311++G (3df) level. The structures have been verified by the
Intrinsic Reaction Coordinate (IRC).
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